Why is a short pin code sufficient on iOS?

Question

iOS

It was necessary to implement encryption of the application database on iOS. At the same time, it is critical that it cannot be accessed both from other applications and through a lost device. Of course, you want to use a convenient, short, digital pin code instead of a strong 12+ character password in a good alphabet.
To unlock iOS itself, this is implemented in the form of a 6-digit pin code, and in the Tinkoff Bank application, they generally managed 4 digits. The question is, how can such keys provide strong encryption even with a complex key derivation function? After all, in theory, all options do not brute force for so long.

Answer 1

The fact is that the pin to the iPhone cannot be sorted out programmatically. 3 times wrong - blocking for a few minutes, etc. up to complete blocking. Those. brute force is not very realistic.